The damage from a dragon's breath may stem from more than just fire. Theres a good amount of examples where one attack does X damage from one source (ie, fire) and Y through another. Maybe dragons put a little more magical oomph into their breath.

Sounds more like elementals just have high resistance. Just to grab numbers, if a Fire Elemental burns at 1500 degrees, it ignores heat lower than that, but still takes damage from heat higher than its own temperature threshold.

I think that what the designers were trying to imply with that passage was an innate difference between a fireball and a breath weapon.

A fireball is a middling-level wizard spell that creates a pressureless globe of fire at the target point. It is specifically not an explosion, though it is often depicted as such. Also, despite the fact that the fire is magically conjured, once the spell goes off it is normal fire for all intents and purposes.

A red dragon's breath weapon, however, is typically depicted as a pressurized gout or blast of supernatural flame that originates at one corner of the target area and washes over the rest of it with sufficient pressure to blast aside anything not vaporised by it. When dealing with breath weapons, I find that "volcanic" is a good way to describe them.

In 3.X, with its fanatical devotion to "type," these both amounted to handfuls of d6s, with no mechanical differentiation between the two other than number of dice, shape of area, and save DC.

The fluff, however, has always described the two effects very differently, and while I fully expect my meat shield or Dex monkey to scoff at the very thought of taking cover in the face of a fireball, I would be sorely disappointed in either of them if they had the same reaction to a breath weapon.

I, for one, welcome a mechanical difference between a fleeting puff of heat from a wizard and the primal fury of a dragon unleashing their breath weapon.

-m4ki; one down, one to go

"Retro is not new.
Retro-fit is not new."--Seeker95,
on why I won't be playing DDN

1. Imbalanced gameplay.Any and all characters must be able to contribute equally both in combat and out of combat at all levels of play. If the Fighters are linear and the Wizards quadratic, I walk.
2. Hardcore simulationist approach. D&D is a game about heroic fantasy. I'm weak and useless enough in real life; I play RPGs for a change of pace. If the only reason a rule exists is because "that's how it's supposed to be", I walk. I don't want a game that "simulates" real life, I want a game that simulates heroic fantasy.
3. Worshipping at false idols (AKA Sacred Cows). If the only reason a rule exists is "it's always been that way", I walk. Now to be clear, I have no problem with some things not changing; my issue is with retaining bad idea simply for the sake of nostalgia.
4. DM vs. players. If the game encourages "gotcha!" moments or treats the DM and players as enemies, adversaries, or problems to be overcome, I walk.
5. Rules for the sake of rules. The only thing I want rules for is the things I can't do sitting around a table with my friends. If the rules try to step on my ability to roleplay the character I want to roleplay, I walk. Furthermore, the rules serve to facilitate gameplay, not to simulate the world.
NOTE: Items in red have been violated.

1. When in doubt, wing it.
2. Keep the story moving. Go with the flow.
3. Sometimes things make the best characters.
4. Always give players lots of things to do.
5. Wherever possible, say ‘yes.’
6. Cheating is largely unnecessary.
7. Don't be afraid to give the characters a fun new toy.
8. Don't get in the way of a good players exchange.
9. Avoid talking too much.
10. Save some details for later.
11. Be transparent.
12. Don't show all your cards.
Words to live by.

"Essentials zigged, when I wanted to continue zagging..." -Foxface on Essentials
"Servicing a diverse fan base with an RPG ruleset - far from being the mandate for 'open design space' and a cavalier attitude towards balance - requires creating a system that /works/, with minimal fuss, for a wide variety of play styles, not just from one group to the next, but at the same table." -Tony_Vargas on design
"Mearls' and Cook's stated intent to produce an edition that fans of all previous editions (and Pathfinder) will like more than their current favourite edition is laudable. But it is also, IMO, completely unrealistic. It's like people who pray for world peace: I might share their overall aims, but I'm not going to hold my breath waiting for them to succeed. When they talk in vague terms about what they'd like to do in this new edition, I mostly find myself thinking 'hey, that sounds cool, assuming they can pull it off', but almost every time they've said something specific about actual mechanics, I've found myself wincing and shaking my head in disbelief and/or disgust, either straight away or after thinking about the obvious implications for half a minute." -Duskweaver on D&D Next

You could think as fire elementals as a stable pattern. The effect of the pattern is fire. A fireball spell uses a totally different pattern to create the same effect, so therefore the basis of the elemental is untouched and unharmed. Conversely, dragonbreath not only createst the effect it also disrupts the pattern, thereby causing damage to the elemental.

So if I had a chalk diagram and I wanted to get it wet. If I use oil, it is now wet, although the chalk itself is unharmed. If I use water I get the same effect, although the pattern is now corrupted.

I have a much simpler answer, it's magic! Not flesh, not electrical nerve impulses and not snow. The premise of the question is what would happen if a humanoid ball of fire given human intelligence by the infusing of magic, that is protected by armor that somehow manages not to melt, wields a weapon that somehow manages not to melt and is not immediately extinguished when it starts running when it encounters a fire breathing dragon. You're not honestly using biophysics and logic to try to answer this are you?

I think the Dragon's breath snuffs out the elemental like an atomic blast snuffs out a candle flame.

It first increases the heat so the elemental burns faster for the duration, then the flames roll over the elemental. This in its self increases the elementals need for oxygen and denies it any access to oxygen.

If you have a water elemental and you turn a firehose on them so that they not have water rushing at them in great volumes at a very high pressure, wouldn't this likely kill the water elemental since the water that forms its body would now be hit by other water and shoved away from its body?

That's a much different experience then swimming around in the ocean, although I imagine that water elementals might also have some problem if they are forced too deep in the ocean and the pressure becomes too much to bear.

Both of these examples assume that the physical concussive force can do harm to the elemental, even if what is going at them in that force is their own element.

Similarly, even if the fire elemental can live inside fire, that doesn't mean having flames shoved /through/ it with giant blasts of wind wouldn't hurt.

Remember; under high enough pressure, water can cut steel. Likewise, out here in the real world, forest fires are often fought by selectively burning down patches of land in a controlled fashion to starve the fire of fuel. Similarly, it is also possible to extinguish a smaller flame by causing a larger explosion nearby it, starving the smaller flame of oxygen enough to snuff it.

Also, I reiterate that there is probably a supernatural factor to the dragon's breath weapon. It wouldn't surprise me if it had a secondary effect of stripping (at least temporarily) fire resistance off the target(s).

-m4ki; one down, one to go

"Retro is not new.
Retro-fit is not new."--Seeker95,
on why I won't be playing DDN

1. Imbalanced gameplay.Any and all characters must be able to contribute equally both in combat and out of combat at all levels of play. If the Fighters are linear and the Wizards quadratic, I walk.
2. Hardcore simulationist approach. D&D is a game about heroic fantasy. I'm weak and useless enough in real life; I play RPGs for a change of pace. If the only reason a rule exists is because "that's how it's supposed to be", I walk. I don't want a game that "simulates" real life, I want a game that simulates heroic fantasy.
3. Worshipping at false idols (AKA Sacred Cows). If the only reason a rule exists is "it's always been that way", I walk. Now to be clear, I have no problem with some things not changing; my issue is with retaining bad idea simply for the sake of nostalgia.
4. DM vs. players. If the game encourages "gotcha!" moments or treats the DM and players as enemies, adversaries, or problems to be overcome, I walk.
5. Rules for the sake of rules. The only thing I want rules for is the things I can't do sitting around a table with my friends. If the rules try to step on my ability to roleplay the character I want to roleplay, I walk. Furthermore, the rules serve to facilitate gameplay, not to simulate the world.
NOTE: Items in red have been violated.

1. When in doubt, wing it.
2. Keep the story moving. Go with the flow.
3. Sometimes things make the best characters.
4. Always give players lots of things to do.
5. Wherever possible, say ‘yes.’
6. Cheating is largely unnecessary.
7. Don't be afraid to give the characters a fun new toy.
8. Don't get in the way of a good players exchange.
9. Avoid talking too much.
10. Save some details for later.
11. Be transparent.
12. Don't show all your cards.
Words to live by.

"Essentials zigged, when I wanted to continue zagging..." -Foxface on Essentials
"Servicing a diverse fan base with an RPG ruleset - far from being the mandate for 'open design space' and a cavalier attitude towards balance - requires creating a system that /works/, with minimal fuss, for a wide variety of play styles, not just from one group to the next, but at the same table." -Tony_Vargas on design
"Mearls' and Cook's stated intent to produce an edition that fans of all previous editions (and Pathfinder) will like more than their current favourite edition is laudable. But it is also, IMO, completely unrealistic. It's like people who pray for world peace: I might share their overall aims, but I'm not going to hold my breath waiting for them to succeed. When they talk in vague terms about what they'd like to do in this new edition, I mostly find myself thinking 'hey, that sounds cool, assuming they can pull it off', but almost every time they've said something specific about actual mechanics, I've found myself wincing and shaking my head in disbelief and/or disgust, either straight away or after thinking about the obvious implications for half a minute." -Duskweaver on D&D Next

Maybe it's just from being one of those "anime kids" (despite being almost 25), but I like the image of some creature standing there in the way of the massive blast of fire, completely confident in his invulnerability. Then there's MORE FLAMES! The flames are BIGGER! MORE POWERFUL! TOO POWERFUL! I...I CAN'T TAKE IT! ARRRRRRGH!!! *see the sillouette from behind, disintegrating in the flames*

Maybe it's just from being one of those "anime kids" (despite being almost 25), but I like the image of some creature standing there in the way of the massive blast of fire, completely confident in his invulnerability. Then there's MORE FLAMES! The flames are BIGGER! MORE POWERFUL! TOO POWERFUL! I...I CAN'T TAKE IT! ARRRRRRGH!!! *see the sillouette from behind, disintegrating in the flames*

:D

I am also of the opinion that since the dragons they mention having the ability to burn off fire resistance are older dragons, that means they are more magically powerful. What it comes down to is the dragons magic, fire based or otherwise, simply overwhelms the inherent magic of the lesser elemental. Between two forces of equivalent type, the smaller always yields or is subsumed into the greater.

Alright my real guess is enough fire makes the original elemental kind of fall apart. Like it becomes one with the fire breadth & becomes nothing more than a few small fires. Destroys the essence that keeps the elemental together. These are just my guesses.

Honestly I see fire elementals as being immune to weapons like being incorporeal, but in turn they can only cause 1d6 or so fire damage (plus catching people on fire)
Since last time I checked you cant cut fire.

Honestly I see elementals being immune to different elements

Like
Earth Immune to Fire (since Im pretty sure you cant burn ground)
Fire Immune to Air (Since wind just adds more to the fire)
Air Immune to Earth (Ground doesnt effect air all that much)
Water Immune to Water (Water would be the black sheep of the group and the only one immune to itself)

What I see in the dragons breath is the pressure that snuffs out the fire elemental, as a high pressure hose would hit a water elemental and blow it up. An air elemental could be blown apart by a sudden gust, and a earth elemental could actually be cut, stabbed, and smashed by normal weapons. The fire ball is really just heat, which won't hurt a fire elemental. Similarly a water elemental would have no trouble surviving in a calm lake. As for the elementals having immunity to each other, moving earth will disrupt air currents, air blows out fire high pressured water gets rid of water, and hot enough fire will melt an earth elemental. If it is high enough temperature it will excite the atoms enough for them to become plasma, at which point the entire molecular structure is blown apart into protons, electrons, and neutrons. It cools down, but the earth isn't going to come back. However, high resistance to other elements makes sense.

#1
Fire elementals are no longer flame-like fire creatures. Fire elementals are like the efreeti who is still flesh and bone but have high fire resistance. All elementals are now like the efreeti and there are no burning flames type elementals.

#2
In the example the reason for the difference between the fireball and the dragonsbreath is amount of damage. If an efreeti has fire resistance 30 then maybe the fireball does no harm BECAUSE the damage does not exceed 30. A dragons breath on the other hand is going to do more than 30 almost always and as such will do damage but 30 less than against a normal human.

All of this other chatter is interesting but off topic. The breath weapon in this example was purely an example of a higher damage dealing fire attack.

See, this silliness is what you get when enough people whine that their extremely narrowed build (for example fire mage) does not "kick ass" all the time. God beware that PCs are trying to cover their weakness. No, the system has to be changed so that they don't have a weakness anymore (or rather, to make it looks as if they are still effective when in reality they are no more effective than before).

So let me get this straight. If I make a fire elemental hotter then I somehow destroy it? Hmmmm, I wonder if that really works.
"Honey, where's my blow torch? I want to see if I can put a fire out with it."

Ok, enough sarcasm. I'm all for a reduction in immunities for most creatures (dragons, giants, etc.), but a creature made of fire should not only be immune to heat based attacks, but it should also get healed/stronger when hit by them. But whatever, I hate the 3.X version of elementals as well. Honestly, how does a creature made entirely of fire get killed by a steel sword?

So let me get this straight. If I make a fire elemental hotter then I somehow destroy it? Hmmmm, I wonder if that really works.
"Honey, where's my blow torch? I want to see if I can put a fire out with it."

Ok, enough sarcasm. I'm all for a reduction in immunities for most creatures (dragons, giants, etc.), but a creature made of fire should not only be immune to heat based attacks, but it should also get healed/stronger when hit by them. But whatever, I hate the 3.X version of elementals as well. Honestly, how does a creature made entirely of fire get killed by a steel sword?

Well you could burn out a fire by incinerating it's fuel.

I agree, something that is just a living flame should be killed most easily by a bucket of water. Except from a game perspective that would really suck.

In palladium games a fire elemental can be harmed by regular water since it is made of flame, though it will take a lot of water to actually douse it.

I can see where 4th ed is going with elementals and it isn't necessarily a bad path to take. It breaks with traditional elementals from other fantasy settings, where an elemental is a being of pure fire, water, air, etc.

Actually, getting rid of immunities is more so to make sure PCs can't just slaughter certain npcs outright when the npc is far stronger then the player characters. Lets say you run into Ragel, a human Sorcerer who specializes in fire attack spells. Ragel is level 12, while the party is around 8th level. The party wizard summons a fire elemental to fight Ragel and then everyone in the party makes a break for it. What is Ragel going to do? all of his damage spells are fire based, so he can't do anything against the fire elemental except fight it with normal weapons. Without his magic, Ragel is basically as powerful as a 12th level commoner with a spear.

To be honest, however, I think the PC wizard should be rewarded for using this tactic, as it is a smart decision on his part to use the weakness of the enemy against him. The big problem with Dungeons and Dragons is that it is too much about balance and not enough about rewarding people for playing smart.

So let me get this straight. If I make a fire elemental hotter then I somehow destroy it? Hmmmm, I wonder if that really works.
"Honey, where's my blow torch? I want to see if I can put a fire out with it."

Ok, enough sarcasm. I'm all for a reduction in immunities for most creatures (dragons, giants, etc.), but a creature made of fire should not only be immune to heat based attacks, but it should also get healed/stronger when hit by them. But whatever, I hate the 3.X version of elementals as well. Honestly, how does a creature made entirely of fire get killed by a steel sword?

I don't disagree with you entirely but I see it kind of like a puddle, when you send a torrent of water at the puddle you replace it's water with the water you sent and it gets separted and spread out. In that sense I can see it work. You simply dissapate the fire elemental's living fire. (Yeah it doesn't work with everything but some things it does)

Lets say you run into Ragel, a human Sorcerer who specializes in fire attack spells. Ragel is level 12, while the party is around 8th level. The party wizard summons a fire elemental to fight Ragel and then everyone in the party makes a break for it. What is Ragel going to do? all of his damage spells are fire based, so he can't do anything against the fire elemental except fight it with normal weapons. Without his magic, Ragel is basically as powerful as a 12th level commoner with a spear.

That's why Ragel is an NPC, and hence takes control of your summoned fire elemental with but a word. You've just made him a friend. Thanks, guys.

Seriously, though, there are dozens of explanations of how fire can be extinguished by fire on this thread alone. If it's still too tough for you, then I suggest you wait for WotC's explanation. It'll likely be quite similar to what we've already provided here, though.

I agree, something that is just a living flame should be killed most easily by a bucket of water. Except from a game perspective that would really suck.

I always figured elementals maintained a connection to their planes to bring in "fuel" if needed. I mean imagine if fire elemental sreally needed to maintain a steady supply of fuel. You could just defeat one by surrounded it with stone walls and waiting for it to burn out. Makes the game rely too much on actual science to have to worry about fuel. But I do think it would be cool if certain creatures required more creative tactics to vanquish, especially something as bizarre as living flame.

I don't disagree with you entirely but I see it kind of like a puddle, when you send a torrent of water at the puddle you replace it's water with the water you sent and it gets separted and spread out. In that sense I can see it work. You simply dissapate the fire elemental's living fire. (Yeah it doesn't work with everything but some things it does)

Err... yeah that's a stretch. I mean you can come up with some kind of explanation since it is all just fantasy. But I don't really want puddle elementals, I want living fire. Something intangible that can't be hacked with a sword but goes screaming in fear from a bucket of water.

Seriously, though, there are dozens of explanations of how fire can be extinguished by fire on this thread alone. If it's still too tough for you, then I suggest you wait for WotC's explanation. It'll likely be quite similar to what we've already provided here, though.

True, anyone can come up with explanations since none of it is real. It just feels lame that attacking something made of fire with fire kills it. Just like killing living flame with a sword in 3.5 feels lame. And it is not "too tough" for people to understand so stop being condescending.

I think too visually it would look quite stunning.

You see the fire-elemental getting cascaded by the roaring fire of the dragon, fire belches out of the cone as it gets stripped off the magical-form of the fire elemental.

It seems to retain it shape, till the end. When the fiery breath of the dragon extinguishes the blackened armour that once held the fire elemental falls to the ground with a heavy clang.

I agree that would be cool, but to me that is not a fire elemental. If it has form enough to hold armor then it is not pure living flame. It is basically a solid form on fire, a burning humanoid, like the Human Torch.

I would like to see the pure raw elementals be more like spirits controlling their respective elements. You could either destroy or try to trap their elemental form, or go after the incorporeal spirit using magical weapons and magic.

I always figured elementals maintained a connection to their planes to bring in "fuel" if needed. I mean imagine if fire elemental sreally needed to maintain a steady supply of fuel. You could just defeat one by surrounded it with stone walls and waiting for it to burn out. Makes the game rely too much on actual science to have to worry about fuel. But I do think it would be cool if certain creatures required more creative tactics to vanquish, especially something as bizarre as living flame.

Hmm... Actually that reminds me of Howl's Moving Castle since there is a evil fire-spirit that will die if it isn't replenished with fresh fuel (firewood).

I always figured elementals maintained a connection to their planes to bring in "fuel" if needed. I mean imagine if fire elemental sreally needed to maintain a steady supply of fuel. You could just defeat one by surrounded it with stone walls and waiting for it to burn out. Makes the game rely too much on actual science to have to worry about fuel. But I do think it would be cool if certain creatures required more creative tactics to vanquish, especially something as bizarre as living flame.

Sure, the elemental keeps a small opening to the elemental plane of fire to feed it its necessary energy/fuel. Then the dragon comes along and being an ancient powerful being brimming with mystic energy breathes on the elemental, burning the elemental's necessary energy/fuel faster than the elemental can replenish it. The tiny planar gate closes as the elemental that needed and sustained it is now gone.